Drafting instrument



March 12, 1957 D. F. BLONDIN DRAFTING INSTRUMENT Filed June 6, 1955 INVENTOR DONALD F BLOND/IV United States Patent DRAFTIN G lNSTRUlVIENT Donald F. Blondin, Grand Haven, Mich.

Application June 6, 1955, Serial No. 513,307

1 Claim. (Cl. 33-174) simple and economical to manufacture.

These and other objects and purposes of this invention will be apparent from the following specification and accompanying drawing.

In the drawings:

Fig. 1 is a top plan view of the drafting instrument.

Fig. 2 is a sectional view on the line 2-2 of Fig. 1.

Fig. 3 is a perspective view of the drafting instrument illustrating the manner in which the instrument is used.

Referring specifically to the drawing, the numeral 1 indicates a generally rectangular body member which can be made or molded from plastic, metal, wood, or any other desired material.

An aperture 2 is provided in the body member here shown in the shape of an isosceles triangle with the perpendicular bisector of the base of said triangle being parallel to the marginal edges of said body member. The underside of the web section 3 of said body member is recessed somewhat from the built-up marginal sections 4 so that the triangle aperture is raised above the paper or other surface on which said body member may be placed.

The marginal sections 4 project substantially above the upper surface of the web 3, forming a pair of rails or guides. Slidably located in contact with the upper face of said web section 3 and in the channel formed between the marginal sections 4, is a slide element 5. The said slide element 5 is slidably retained in said channel by its beveled longitudinal edges 6 which enter and slidably fit within longitudinal grooves 7 in the marginal sections 4.

A recessed surface 8 on said slide element 5 is provided with grooves or ridges 9 to provide a friction surface to facilitate movement of said slide element.

The web section 3 of the body member 1 is provided with a centerline 10 for aligning the drafting instrument with lines previously drawn by the draftsman. A scale 11 consisting of parallel lines is provided on the upper face of the web section 3 so that the slide element 5 can be positioned and repositioned to the same location.

A hole 12 is provided through the web section 3 of said 2 body member to receive the point of a pencil for rapid positioning of said drafting instrument by the user. It may also be used for hanging the instrument when not in use.

Fig. 3 depicts the manner in which the drafting instrument is used. The drafting instrument: is placed on the paper or surface on which a symbol is to be drawn and is held in position by the thumb and one or more fingers of the user. The slide element 5 is then positioned to cover or expose the desired area of the aperture. The opening thus exposed is for the reception of a pen or pencil held in the other hand of the user. It will thus be apparent that by moving said slide element 5 with respect to the body member ll that largeror smaller opening is provided limited only by the size of the aperture 2. Raising the aperture-d web above the paper or other surface on which said body member may be placed, as hereinbefore described, is for the purpose of preventing smearing of ink when a pen is used by the user.

The drafting instrument which is the subject of this invention lends itself to economical manufacturing in that there are only two parts which may easily be made as for example, from plastic or from metal stampings.

it will be apparent that by lengthening the body membcr 4-, that additional apertures may be provided in the web section 3 and that the slide element 5 or additional slide elements can be used in conjunction with said additional apertures to provide an instrument for producing several styles of arrowheads or other drafting symbols. It will also be recognized that this invention is not limited to instruments for marking triangular representations but may be applied to the making of indicia which lends itself to change in size or shape simply by adjusting the position of one edge of the indicia.

It will also be apparent that the drafting instrument described could be furnished with a spring adjustment or adjustable side guide for controlling the friction against the slide element 5.

It will be recognized that other changes, additions, or omissions can be incorporated in a drafting instrument of the type described. which will fall within the scope of the invention claimed.

I claim as my invention:

A drafting instrument comprising: a body member including parallel marginal rails projecting above and below a web, said rails havin undercut sides; a slide element adapted to sent between said rails and to have its margins received into the undercut sides of said rails; said web having a triangular aperture with its apex projecting away from said slide element, said aperture being adapted to be progressively covered by said slide element; said web having inscribed thereon a longitudinal centerline parallel to said marginal rails and transverse gradation lines; said web also having therein a second aperture centered about said centerline and adapted to receive the point of a pencil for rapid positioning of said drafting instrument.

References Cited in the file of this patent UNITED STATES PATENTS 1,202,041 Fabricus Oct. 24, 1916 l,5'74,953 Wood Mar. 2, 1926 1,742,684 Bowman Jan. 7, 1930 2,458,072 Hall Jan. 4, 1949 2,604,702 Collins July 29, 1952 2,702,944 Lane Mar. 1, 1953 

